Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$85.93	9.365%	$93.9773	$93.98	$94.00	$94.00
Purchase #2	$222.38	8.149%	$240.5017	$240.50	$240.50	$240.50
Purchase #3	$194.69	11.727%	$217.5213	$217.52	$217.50	$217.50
Purchase #4	$215.64	3.356%	$222.8769	$222.88	$222.90	$222.90
Purchase #5	$234.65	8.620%	$254.8768	$254.88	$254.90	$254.90
Purchase #6	$66.68	7.124%	$71.4303	$71.43	$71.45	$71.40
Purchase #7	$55.39	7.715%	$59.6633	$59.66	$59.65	$59.70
7 purchase totals =	$1,075.36		$1,160.8476	$1,160.85	$1,160.90	$1,160.90